线性盈亏分析模型一般可用图和()来描述
参考答案:函数
—John,when will you pay a visit to that place of interest?
—I can’t decide at present. _______.
A.It just depends
B.It’s up to you
C.Take your time
D.I beg your pardon
教师的情绪对课堂气氛有何影响